[英]How to download pdf file and redirect to home page in Spring mvc
以下代碼工作正常,沒有錯誤,但不能按要求工作..
問題 1:我想下載 pdf 文件並重定向到主頁(url:../)。當我訪問 url(../admin/generate_pdf) 時
問題 2:當我取消注釋 Pdfdemo.java 中的注釋行時,它會給我一個錯誤 404 頁面未找到。
pdf演示文件
public class Pdfdemos {
private static String USER_PASSWORD = "password";
private static String OWNER_PASSWORD = "lokesh";
public String generate_pdf() {
try {
String file_name="d:\\sanjeet7.pdf";
Document document= new Document();
PdfWriter writer=PdfWriter.getInstance(document, new FileOutputStream(file_name));
// writer.setEncryption(USER_PASSWORD.getBytes(),
// OWNER_PASSWORD.getBytes(), PdfWriter.ALLOW_PRINTING |PdfWriter.ALLOW_ASSEMBLY|
// PdfWriter.ALLOW_COPY|
// PdfWriter.ALLOW_DEGRADED_PRINTING|
// PdfWriter.ALLOW_FILL_IN|
// PdfWriter.ALLOW_MODIFY_ANNOTATIONS|
// PdfWriter.ALLOW_MODIFY_CONTENTS|
// PdfWriter.ALLOW_SCREENREADERS|
// PdfWriter.ALLOW_ASSEMBLY|
// PdfWriter.ENCRYPTION_AES_128, 0);
document.open();
document.add(new Paragraph(" "));document.add(new Paragraph(" "));
String days_in_week[]= {"monday","tuesday","webnesday","thursday","friday","saturday"};
int period=8;
String user="springstudent";
String pass="springstudent";
String jdbcUrl="jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false";
String driver="com.mysql.jdbc.Driver";
Connection myconn=DriverManager.getConnection(jdbcUrl,user,pass);
PreparedStatement ps=null;
ResultSet rs=null;
String query="select * from class_t";
ps=myconn.prepareStatement(query);
rs=ps.executeQuery();
while(rs.next()) {
Paragraph para=new Paragraph("Time table for class"+rs.getString("class")+rs.getString("section"));
document.add(para);
System.out.println(rs.getInt("id"));
PdfPTable table=new PdfPTable(period+1);
for(int i=0;i<days_in_week.length;i++) {
for(int j=0;j<period+1;j++) {
if(j==5) {
table.addCell("recess");
}else {
table.addCell("this is "+j);
}
}
}
document.add(table);
document.newPage();
}
document.close();
System.out.println("finish");
return file_name;
}catch(Exception e) {
System.out.println(e);
}
return null;
}
}
Generate_pdf_controller.java
@Controller
@RequestMapping("/admin/generate_pdf")
public class Generate_pdf_Controller {
@GetMapping("/online")
public String generating_pdf(Model theModel) {
System.out.println("hello");
CustomerServiceImpl pal=new CustomerServiceImpl();
Pdfdemos pal1=new Pdfdemos();
String xx=pal1.generate_pdf();
return "redirect:/";
}
}
創建和下載 PDF 的簡化版本:
@Service
public class PdfService {
public InputStream createPdf() throws Exception {
ByteArrayOutputStream out = new ByteArrayOutputStream();
Document document = new Document(PageSize.A4, 50, 50, 50, 50);
PdfWriter writer = PdfWriter.getInstance(document, out);
writer.setEncryption("user_password".getBytes(), "owner_password".getBytes(),
PdfWriter.ALLOW_PRINTING |
PdfWriter.ALLOW_ASSEMBLY |
PdfWriter.ALLOW_COPY |
PdfWriter.ALLOW_DEGRADED_PRINTING |
PdfWriter.ALLOW_FILL_IN |
PdfWriter.ALLOW_MODIFY_ANNOTATIONS |
PdfWriter.ALLOW_MODIFY_CONTENTS |
PdfWriter.ALLOW_SCREENREADERS |
PdfWriter.ALLOW_ASSEMBLY |
PdfWriter.ENCRYPTION_AES_128, 0);
document.open();
document.add(new Paragraph("My example PDF document"));
// some logic here
document.close();
return new ByteArrayInputStream(out.toByteArray());
}
}
@Controller
@RequestMapping("/admin/generate_pdf")
public class PdfController {
@Autowired
private PdfService pdfService;
@GetMapping("/online")
public void generatePdf(HttpServletResponse response) throws Exception {
response.setContentType("application/pdf");
response.setHeader("Content-Disposition", "attachment; filename=\"mydocument.pdf\"");
InputStream pdf = pdfService.createPdf();
org.apache.commons.io.IOUtils.copy(pdf, response.getOutputStream());
response.flushBuffer();
}
}
重定向怎么樣,正如我在評論中所說,你可以在前端使用 JS(在調用/admin/generate_pdf/online
url 之后)。 您不能同時下載文件和進行刷新/重定向。
只是為了得到pdf(從本地文件系統下載到瀏覽器),這段代碼就足夠了:
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@RequestMapping("/admin/generate_pdf")
public class PdfController {
@GetMapping(value = "/online", /*this is "nice to have" ->*/ produces = MediaType.APPLICATION_PDF_VALUE)
@ResponseBody // this is important, as the return type byte[]
public byte[] generating_pdf() throws IOException {//exception handling...
System.out.println("hello");//logging
// re-generate new file if needed (thread-safety!)...
// ..and dump the content as byte[] response body:
return Files.readAllBytes(Paths.get("d:\\sanjeet7.pdf"));
}
}
...如果您需要“刷新”,您可以“重寫”文件/重新調用您的服務,但可能仍然不是“線程最安全”的解決方案。
編輯:無需進一步配置(端口/上下文根/...),您應該在以下位置訪問: http://localhost:8080/admin/generate_pdf/online
如果您想“操作更接近字節”並使用void
返回類型/無@ResponseBody
並想要額外的重定向(待測試),我認為這應該仍然有效:
@Controller
public class ... {
@GetMapping(value = ..., produces ...)
//no request body, void return type, response will be autowired and can be handled
public void generatePdf(javax.servlet.http.HttpServletResponse response) throws ... {
java.io.OutputStream outStr = response.getOutputStream();
// dump from "somewhere" into outStr, "finally" close.
outStr.close();
//TO BE TESTED:
response.sendRedirect("/");
}
}
.. 甚至(返回“視圖名稱”+ 對 outputStream 進行操作):
@GetMapping(value = ..., produces = "application/pdf")
//return a "view name" (!), and you can inject (only) the outputstream (without enclosing response)
public String generatePdf(java.io.OutputStream outputstream) throws... {
// ... do your things on outputstream, IOUtils is good...
// close the stream(?)
// ..and
return "redirect:/"; // to a redirect or a view name.
// .... (in a "spring way", which could also save you some "context path problems"
} ...
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